Automatic elevating mechanism for a paper feed platform of an automatic paper feed device for use with a photocopying machine, printing press, or the like

ABSTRACT

When the height of a stack of papers to be copied or printed falls below a predetermined level, the level of the stack is sensed by a sensing roller which closes the circuit for a solenoid through a microswitch attached to the sensing roller. A blocking plate is pulled downwardly by the solenoid and a constantly reciprocating engaging pawl is thereby allowed to engage a ratchet wheel, thereby moving upwardly a rack in mesh with a pinion integral with the ratchet wheel, whereby a paper feed platform supported by the rack can be elevated up to a predetermined level.

United States Patent I-Iideo Hashimoto Koshigaya-shi, Japan Appl. No. 755,539

Filed Aug. 27, 1968 Inventor AUTOMATIC ELEVATING MECHANISM FOR A PAPER FEED PLATFORM OF AN AUTOMATIC PAPER FEED DEVICE FOR USE WITH A PHOTOCOPYING MACHINE, PRINTING PRESS,

OR THE LIKE 3 Claims, 2 Drawing Figs.

U.S. c1.....

Primary ExaminerJoseph Wegbreit Attorney-Burgess, Ryan and Hicks ABSTRACT: When the height of a stack of papers to be copied or printed falls below a predetermined level, the level of the stack is sensed by a sensing roller which closes the circuit for a solenoid through a microswitch attached to the sensing roller. A blocking plate is pulled downwardly by the solenoid and a constantly reciprocating engaging pawl is thereby allowed to engage a ratchet wheel, thereby moving upwardly a rack in mesh with a pinion integral with the ratchet wheel, whereby a paper feed platform supported by the rack can be elevated up to a predetermined level.

PATENTEUHAYZSIQYI 3580.567

FIG. 2

25 INVENTOR H I'DEO HAsHiMoTo ATTORNEY AUTOMATIC ELEVATING MECHANISM FOR A PAPER FEED PLATFORM OF AN AUTOMATIC PAPER FEED DEVICE FOR USE WITH A PHOTOCOPYING MACHINE, PRINTING PRESS, OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to automatic elevating mechanism of a paper feed platform for use with a photocopying machine, a printing press or the like of the type wherein when the paper or sheet feed level is lowered as papers or sheets are fed, a paper or sheet feed platform is automatically elevated so that the paper or sheet feed level can be always maintained at a predetermined level.

In the conventional paper or sheet platform elevating mechanism of the type described, a reciprocating engaging pawl mechanically engages with a feed roller so as to intermittently rotate the ratchet wheel depending upon the level of the feed roller, whereby the paper or sheet platform is elevated through a pinion and rack assembly actuated by the rotation of the ratchet wheel. In this case, the ratchet wheel is provided with a pawl for preventing the reverse rotation of the ratchet wheel so as to ensure the positive rotation of the ratchet wheel in one direction. However, when the feed roller is situated at its normal level or position, the engaging pawl does not engage with the ratchet wheel so that the reciprocating motion of the engaging pawl is not transmitted to the ratchet wheel, whereby the level of the paper or sheet feed platform remains unchanged. When the uppermost one of the stack of sensitive papers to be copied or sheets to be printed is fed sequentially into the photocopying machine or the printing press so that the level of the paper or sheet feed level is gradually lowered, the level or the position of the feed'roller is also lowered. Therefore, the engaging pawl in mechanical engagement with the feed roller is displaced so as to engage with the ratchet wheel so that the reciprocating motion of the engaging pawl is transmitted to the ratchet wheel, whereby the paper or sheet feed platform is elevated.

As described hereinabove, in the conventional automatic paper or sheet feed platform elevating mechanism, the level or position of the paper or sheet feed level is detected by means of the feed roller itself. Therefore, in order that a paper or a sheet positioned on the top of the stack of papers or sheets may be positively separated from the next paper or sheet of the stack of papers or sheets and then fed into the photocopying machine or printing press one by one, the pressure or force exerting upon the paper or sheet from the feed roller must be always constant. However, in the conventional elevating mechanism of the type described, when the engaging pawl is in engagement with the ratchet wheel, this engaging force is transmitted to the feed roller mechanically coupled with the engaging pawl so that the aforementioned pressure or force is increased, whereby there is a fear that two papers or sheets are fed into the machine or printing press at the same time.

SUMMARY OF THE INVENTION In view of the above, one of the objects of the present invention is to provide an independent sensing member or means for sensing the level of the paperor sheet feed so as to control the rotation of the ratchet wheel by the engaging pawl through the sensing member or means in order to avoid variations in the pressure or force of the feed roller upon the paper or the sheet.

According to the present invention, when the paper or sheet feed level (and therefore the sensing member or means) is located at its normal position, the engagement of the engaging pawl with the ratchet wheel is blocked by a blocking plate so that the reciprocating motion of the engaging pawl is not transmitted to the ratchet wheel. On the other hand, when the paper or sheet feed level (and therefore the sensing member or means) drops below a predetermined level the engaging pawl is caused to engage with the ratchet wheel through the action of a solenoid which removes the blocking plate in response to the closing of a microswitch so as to elevate the paper or sheet feed platform. The upward movement of the paper or sheet feed platform is continued until the sensing member or means returns to its normal position so that the aforementioned microswitch is opened so as to deenergize the solenoid and thereby release the engaging pawl from its engagement with the ratchet wheel.

According to the present invention, the aforementioned reciprocating motion of the engaging pawl is imparted by a rotating eccentric so that it is possible that the sensing member or means can control the aforementioned eccentric rotation through said microswitch. whereby the level of the paper or sheet feed platform may be suitably adjusted.

Another object of the present invention is to provide an elevating mechanism of a paper or sheet feed platform of the type described, eliminating completely the above described disadvantages.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side view illustrating the automatic sheet elevating mechanism for a sheet feeding machine according to the present invention applied to a photocopying machine; and

FIG. 2 is an electrical circuit including a solenoid utilized in the aforementioned mechanism.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, a copy sheet platform 2 is disposed on a machine frame member 1 of a photocopying machine for vertical movement and a stack of sensitive papers 3 is placed upon the sheet feed platform 2. The sheet feed platfonn is adapted to be automatically raised, as the height of the stack of the sensitive papers is decreased, by means of an automatic elevating mechanism for the sheet feed platform which will be described in more detail hereinafter in order that the uppermost sensitive paper of the stack of sensitive papers 3 (that is, the next sensitive paper to be fed into the photocopying machine) may be maintained at the same level all the time. Reference numeral 4 designates a feed roll. An original is fed into the nip between an original feed roller 6 and an original transport belt 7 as indicated by the arrow 5. In this original transportation path is disposed a microswitch 8 for detecting the transportation of the original. When the leading edge of the original contacts a sensor 9 of the microswitch 8 the microswitch 8 produces a signal for rotating the feed roller 4 (the actuating mechanism is not shown). The uppermost sensitive paper of the stack of sensitive papers 3 is transported upon the upper side of a sensitive paper transport belt 10 and is superimposed with the original to be transported from the original transport belt 7 so that the superimposed original-sensitive paper may be advanced to an exposing device provided within the photocopying machine. To the paper feed platform 2 is securely fixed a depending plate 11 extending downwardly therefrom and being provided with a slit 12 extending within the depending plate 11 downwardly. Within this slit 12 are loosely fitted pins 13 and 14 which in turn are securely fixed to the frame member 1 so that the vertical movement of the paper feed platform 2 is guided by the slit l2 and the pins 13 and 14. One side of the depending plate 11 is a rack 15. A shaft 16 securely fixed to the frame member 1 carries rotatably a ratchet wheel 17 and a pinion 18 which is fixedly secured to the ratchet wheel 17 and is meshed with the aforementioned rack 15.

Above the ratchet wheel 17 is disposed a pawl 19 adapted to engage the ratchet wheel 17, and this pawl 19 continually reciprocates in the directions shown by the double pointed arrow by means of a shaft 21 which is eccentrically and fixedly secured to a rotary wheel 20. A blocking plate 22 which is disposed near to the engaging pawl 19 and extends vertically has one end thereof engaged with a tension spring 23 which in turn is fixedly secured to the frame member 1. At the lower end of the blocking plate 22 is provided a solenoid plunger 24 and a solenoid 25 is disposed at such a position as to surround the solenoid plunger 24. The blocking plate 22 is provided with a branched arm portion 26 which has a horizontal upper side face upon which is carried a pin 27 fixedly secured to the engaging pawl 19. When the solenoid 25 is not energized, that is when the solenoid plunger is not pulled downwardly by the solenoid 25, the connecting plate 22 is lifted upwardly by means of the tension spring 23 so that the pin 27 is also raised upwardly by the branched arm portion 26, thereby causing the engaging pawl 19 to elevate, whereby the engagement of the pawl 19 with the ratchet wheel 17 is released. On the other hand, when the solenoid is energized, so as to pull down the solenoid plunger 24, the connecting plate 22 is caused to move downwardly against the tension spring 23 so that the engaging pawl 19 is moved downwardly thereby engaging with the ratchet wheel 17.

in addition, a pawl 28 made in the form of a bell crank is adapted to engage with the ratchet wheel 17 to prevent reverse rotation thereof. An actuating bar 29 adapted to control the contact of the aforementioned pawl 28 with the ratchet wheel 17 is engaged with one end of one arm of the lever. By means of a compression spring 30 fixedly secured at its upper end to the actuating bar 29, the pawl 28 for preventing the reverse motion of the ratchet wheel 17 is subjected to the torque in the clockwise direction (as seen in FIG. 1) so that positive engagement with the ratchet wheel 17 is ensured. Reference numeral 31 designates a pin fixedly secured to the actuating bar 29 and adapted to act upon pawl 28 when the actuating bar 29 is moved upwardly so as to rotate the pawl 28 in the counterclockwise direction (as shown in FIG. 1), thereby releasing the pawl 28 from the engagement with the ratchet wheel 17. Reference numeral 32 designates a microswitch adapted to be opened by the movement of the pawl 28 in a counterclockwise direction. Independently of the feed roller 4, there is disposed upon the uppermost sensitive paper of the stack of sensitive papers 3 a sensor roller 33 for sensing the height of the stack of sensitive papers 3. The sensor roller 33 is provided with a microswitch 34 which is adapted to be opened by upward movement of the sensor roller 33.

As shown in FIG. 2, the solenoid 25 and the microswitches 32 and 34 are interconnected in series with each other so that the attracting motion of the solenoid 25 is interrupted by opening either of the microswitches 32 and 3d.

The mode of operation of the automatic elevating mechanism for the paper feed platform constructed as described hereinabove will be described. To lower the paper feed platform 2 the actuating bar 29 is moved upwardly so that the engagement of the reverse rotation prevention pawl 28 with the ratchet wheel 17 is released as the pin 31 rotates the bellcrank. The pawl 28 is thereby caused to rotate in the counterclockwise direction so as to open the microswitch 32, whereby the solenoid circuit is opened. Therefore, the solenoid 25 is not energized so that the blocking plate 22 is lifted by the spring 23, thereby releasing the engagement of the pawl 19 with the ratchet wheel 17. Consequently, both the ratchet wheel 17 and the pinion 18 secured thereto are permitted to rotate clockwise about the shaft 16 so that the depending plate 11 and the paper feed platform 2 are caused to move to the lowest position. In this position a stack of sensitive papers whose ends are aligned with respect to each other are placed upon the feed paper platform and the feed roller 4 as well as the sensor roller 33 are positioned upon said stack of sensitive papers.

Next the actuating bar 29 is pushed down to its original position. By this means, the reverse rotation prevention pawl 28 is made to engage with the ratchet wheel 17 so as to prevent the reverse rotation of the ratchet wheel 17 and at the same time the microswitch 32 is closed so that the solenoid circuit shown in FIG. 2 is closed or established. At this time, when the uppermost sensitive paper of the stack of the sensitive papers 3 is lower than the normal paper feed level, then the microswitch 34 of the sensor roller 33 is closed to close the circuit shown in FIG. 2 so that the solenoid 25 is energized. Consequently, the solenoid plunger 24 is pulled down, so that the blocking plate 22 is also moved downwardly against the spring 23, thereby engaging the engaging pawl 19 with the ratchet wheel 17. Since the engaging pawl 19 is reciprocating as described hereinbefore by means of the rotary wheel 20 which is rotated by the driving mechanism of the photocopying machine (not shown), the ratchet wheel 17 is caused to intermittently rotate. The rotation of the ratchet wheel 17 causes the paper feed platform 2 be moved upward by the pinion 18 and the rack 15. Consequently this upward movement of the paper feed platform brings the paper feed level, (that is, the position of the sensor roller) to its normal position (the optimized paper feeding position) so that the microswitch 34 is actuated to open the circuit shown in FIG. 2, whereby the energization of the solenoid 25 ceases, thereby stopping the upward movement of the paper feed platform 2.

Next when the original is fed as shown by the arrow 5, the feed roller 4 is actuated by the sensing microswitch 8 so that the uppennost sensitive paper of the stack of sensitive papers 3 is advanced forwardly for exposure. This advancing operation is repeatedly cycled. And when the height of the stack of sensitive papers 3 becomes lower than a predetermined height, then the sensor roller 33 actuates the microswitch 34 so that the solenoid circuit shown in FIG. 2 is closed. Therefore, the solenoid 25 is energized so that the connecting plate 22 is pulled downwardly by the solenoid plunger 24 thereby engaging the engaging pawl 19 with the ratchet wheel 17. Therefore, the upward movement of the paper feed platform 2 is started again in the manner as described hereinbefore through the pinion 18 and the rack 15.

As described hereinbefore, the paper feed platform is caused to move upwardly intermittently during the time when the sensitive papers are fed into the photocopying machine successively so that the uppermost sensitive paper of the stack of sensitive papers 3 upon the platform 2 is always maintained at the optimized paper feeding level.

Alternatively, instead of the engaging and releasing operation between the engaging pawl 19 and the ratchet wheel 17, the height of the paper feed platform 2 may be conveniently adjusted by controlling the rotation of the rotary wheel 20 driven by the driving mechanism of the machine. In this case, the connecting plate 22 provided with the branched arm portion 26, the tension spring 23, the solenoid plunger 24, the solenoid 25 and the pin 27 may be eliminated.

The present invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. In an automatic elevating mechanism for a vertically movable paper feed platform comprising a vertically movable rack attached to the paper feed platform in supporting relation thereto, a pinion meshed with the rack and rotatable about a fixed axis, a ratchet wheel connected to the pinion for rotation therewith, a reciprocable pawl placed to engage the teeth of the ratchet wheel and rotate said ratchet wheel in lifting direction to cause the rack to rise, a reverse rotation preventing pawl movable into an engaged position in which said reverse rotation prevention pawl engages the ratchet wheel and prevents said ratchet wheel from rotating in a lowering direction opposite to the lifting direction, a blocking member movable between a blocking position in which said blocking member prevents engagement of the reciprocable pawl with the ratchet wheel and a nonblocking position in which said blocking member allows said engagement, sensing means for detecting the level of the uppermost sheet of paper on the paper feed platform, and control means connected to said sensing means for moving the blocking member from the blocking to the nonblocking position when the sensing means detects absence of said uppermost sheet of paper at a preselected level and from the nonblocking to the blocking position when the sensing means detects the presence of said uppermost sheet of paper at the preselected level, the improvement comprising first means for movingthe reverse rotation prevention pawl to a disengaged position in which said pawl does not prevent the ratchet wheel from rotating in the lowering direction;

second means for moving the reciprocable pawl out of engagement with the ratchet wheel in response to movement of the reverse rotation prevention pawl to the disengaged position; and

third means for guiding movement of the paper feed platform downward into a loading position upon movement of the reverse rotation prevention pawl into the disengaged position and movement of the reciprocable pawl out of engagement with the ratchet wheel.

2. The device of claim 1 comprising manually operable control means for activating the first means.

3. In an automatic elevating mechanism for a vertically movable paper feed platform comprising a vertically movable rack attached to the paper feed platform in supporting relation thereto, a pinion meshed with the rack and rotatable about a fixed axis, a ratchet wheel connected to the pinion for rotation therewith, a reciprocable pawl placed to engage the teeth of the ratchet wheel and rotate said ratchet wheel in lifting direction to cause the rack to rise, a reverse rotation preventing pawl movable into an engaged position in which said reverse rotation prevention pawl engages the ratchet wheel and prevents said ratchet wheel from rotating in a lowering direction opposite to the lifting direction, a blocking member movable between ablocking position in which said blocking member prevents engagement of the reciprocable pawl with the ratchet wheel and a nonblocking position in which said blocking member allows said engagement, the improvement comprising resilient means urging the blocking member into the blocking position;

a solenoid connected to the blocking member adapted for activation by a signal current, said solenoid when so activated moving the blocking member into the nonblocking position;

sensing means for detecting the level of the uppermost sheet of paper on the paper feed platform and transmitting the signal current to the solenoid through a signal-transmission circuit when said level falls below a predetermined position;

manually operable means for moving the reverse rotation preventing pawl into a disengaged position in which said reverse rotation preventing pawl does not prevent rotation of the ratchet wheel; and

switch means for breaking the signal transmission circuit when the reverse rotation preventing pawl is moved into the disengaged position, thereby inactivating the solenoid and allowing the resilient means to move the blocking member into the blocking position. 

1. In an automatic elevating mechanism for a vertically movable paper feed platform comprising a vertically movable rack attached to the paper feed platform in supporting relation thereto, a pinion meshed with the rack and rotatable about a fixed axis, a ratchet wheel connected to the pinion for rotation therewith, a reciprocable pawl placed to engage the teeth of the ratchet wheel and rotate said ratchet wheel in lifting direction to cause the rack to rise, a reverse rotation preventing pawl movable into an engaged position in which said reverse rotation prevention pawl engages the ratchet wheel and prevents said ratchet wheel from rotating in a lowering direction opposite to the lifting direction, a blocking member movable between a blocking position in which said blocking member prevents engagement of the reciprocable pawl with the ratchet wheel and a nonblocking position in which said blocking member allows said engagement, sensing means for detecting the level of the uppermost sheet of paper on the paper feed platform, and control means connected to said sensing means for moving the blocking member from the blocking to the nonblocking position when the sensing means detects absence of said uppermost sheet of paper at a preselected level and from the nonblocking to the blocking position when the sensing means detects the presence of said uppermost sheet of paper at the preselected level, the improvement comprising first means for moving the reverse rotation prevention pawl to a disengaged position in which said pawl does not prevent the ratchet wheel from rotating in the lowering direction; second means for moving the reciprocable pawl out of engagement with the ratchet wheel in response to movement of the reverse rotation prevention pawl to the disengaged position; and third means for guiding movement of the paper feed platform downward into a loading position upon movement of the reverse rotation prevention pawl into the disengaged position and movement of the reciprocable pawl out of engagement with the ratchet wheel.
 2. The device of claim 1 comprising manually operable control means for activating the first means.
 3. In an automatic elevating mechanism for a vertically movable paper feed platform comprising a vertically movable rack attached to the paper feed platform in supporting relation thereto, a pinion meshed with the rack and rotatable about a fixed axis, a ratchet wheel connected to the pinion for rotation therewith, a reciprocable pawl placed to engage the teeth of the ratchet wheel and rotate said ratchet wheel in lifting direction to cause the rack to rise, a reverse rotation preventing pawl movable into an engaged position in which said reverse rotation prevention pawl engages the ratchet wheel and prevents said ratchet wheel from rotating in a lowering direction opposite to the lifting direction, a blocking member movable between a blocking position in which said blocking member prevents engagement of the reciprocable pawl with the ratchet wheel and a nonblocking position in which said blocking member allows said engagement, the improvement comprising resilient means urging the blocking member into the blocking position; a solenoid connected to the blocking member adapted for activation by a signal current, said solenoid when so activated moving the blocking member into the nonblocking position; sensing means for detecting the level of the uppermost sheet of paper on the paper feed platform and transmitting the signal current to the solenoid through a signal-transmission circuit when said level falls below a predetermined position; manually operable means for moving the reverse rotation preventing pawl into a disengaged position in which said reverse rotation preventing pawl does not prevent rotation of the ratchet whEel; and switch means for breaking the signal transmission circuit when the reverse rotation preventing pawl is moved into the disengaged position, thereby inactivating the solenoid and allowing the resilient means to move the blocking member into the blocking position. 